MEP Elements can be created using the Revit API.
Many elements related to duct, pipe and electrical systems can be created using the following methods available in the Autodesk.Revit.Creation.Document class:
Other MEP elements, such as pipes, can only be created using the static Create() method of its corresponding class. Some MEP elements, such as ducts, can be created by a static method of the corresponding class (i.e. Duct) or by a method of the Autodesk.Revit.Creation.Document class. For these elements, the static Create() method is preferred.